Turbine



March 6, 1934. F. LJUNGSTROM TURBINE Filed Oct. 15, 1932 2 Sheets$heet lINVENTOR ATTORNEYS.

March 6, 1934. F. LJUNGSTROM TURBINE Filed Oct. 15. 1932 2 Sheets-Sheet2 dam turbines of this type Patented Mar. 6, 1934 UNITED STATES TURBINEFredrik Lju'n'gstriim,

corporation of Sweden Application October 15,

Lidingo, Sweden, assignor to Aktiebolaget Spontan,

Stockholm, Sweden, 2.

1932, Serial No. 638,025

In Sweden October 17, 1931 6 Claims.

My present invention relates to radial flow steam or gas turbines of thedouble rotation type, i. e., with rotors running in opposite directions.

It has previously been a common opinion that are not adapted to effecthigh power output or for handling admission steam of high pressure.

The principal object of my invention is to provide an economicallyworking radial flow double rotation turbine which may be built for thehighest initial pressures used, i. e., for pressures of 50-100 atm., andfor very large capacities, for instance 100,000 or more at 3,000revolutions per minute, without necessitating the division of theturbine into a plurality of sections with a plurality of outlet areasfor the exhaust steam as has been necessary hitherto for turbines ofsuch capacities.

A further object of my invention is to provide a turbine of the typereferred to, the blades of which are of such shape and its outletconduits so devised that large steam passages are to be found within theturbine and its tapping or extraction conduits, while requiring only alimited axial extension of the turbine system, thus eliminatinginjurious vibrations in spite of very high power and high numbers ofrevolution.

For this reason I provide the turbine with a plurality of chambers inthe side plates communicating with different tapping or extractionpoints within the turbine, from which chambers I conduct the steamquantities withdrawn from difierent temperature levels of the turbine toa plurality of feed-water preheaters for the steam gen erators of theplant, i. e., the steam boiler said preheaters being connected inseries. The extraction lines extending from said chambers are dividedinto a plurality of conduits, particularly for the lowest extractionstage, where large steam volumes are to be handled, and said conduitslead to a common annular collection chamber inside the turbine casing,from which chamber the extraction steam is led by a single conduit tothe outside of the turbine casing.

The invention will be more fully described with reference to theaccompanying drawings in which connection also other featurescharacterizing my invention will be set forth.

In the drawings:--

Fig. l is a side view of the main parts of a steam turbine plant showingmy improved turbine interconnected between two electricturbo-generators;

Figs. 2 and 3 are sectional views taken along the lines 2-2 and 3-3,respectively, of Fig. 1, and

Fig. 4 is an axial section through part of the turbine system from whichwill be seen not only the blading of the turbine but also the connectionof the inlet and outlet conduits for the same.

In the drawings reference character 2 designates the total inner systemof the turbine (see Fig. 1). This system consists mainly of two socalledside plates 3 and 4 (see Fig. 4) which are in a known manner connectedto the end covers 7 and 8 of the generators 5 and 6 and thus through thegenerators to the cover or housing 9 surrounding the turbine aggregate.The side plates 3 and 4 are provided with so-called labyrinth plates 10and 11 cooperating with corresponding plates 12 and 13 connected withturbine discs 14 and 15, respectively, which in turn are rigidlyconnected to the shafts of the generators. Each one of these turbinediscs are in known manner provided with a number of blade rings or bladerows which are so devised and arranged relatively to each other that onpassing of the steam through the turbine system said discs are caused torotate in opposite directions relatively to each other, i. e. a doublerotation is obtained.

Each one of the side plates 3 and 4 is provided with two chambersseparated from each other, i. e. the side plate 3 with'chambers 16 and17 and plate 4 with chambers 18 and 19. These chambers, as will be morefully described in the following, communicate with different stages ofthe turbine system by means of channels through the turbine discs orlabyrinth plates, respectively, and a number of conduits are connectedto said chambers as will be seen from Figs. 2, 3 and 4, through whichsteam is admitted to or withdrawn from the turbine. In order to increasethe thermal efliciency of a steam plant of the kind referred to, it isdesirable to provide a plurality of preheaters (not shown in thedrawings) in which the feed water is successively heated from onetemperature to another by means of steam withdrawn from the turbine atdifferent stages of expansion therein, so that the first preheating ofthe feeding water takes place by steam withdrawn from one of the lowerpressure stages of the turbine, i. e. relatively to the expansion of thesteam one of the last stages, and the further preheating is done bysteam withdrawn from expansion stages near to the centre of the turbine,i. e. by steam of increasing temperature.

In order to facilitate the arrangement of a plurality of such tapping orextraction points, my turbine is, as above mentioned, so devised thatthe admission of steam thereto takes place through one of its sideplates only. As apparent from the drawings, plate 3 is provided with achamber 16 to which the high pressure steam from the steam boilers (notshown in the drawings) is introduced through conduit 26 and its branches21, 22 and 27. From. chamber 16 the steam is conducted through channels20 in the turbine disc 14 to the high pressure stage 29 of with respectto its temperature, comes next to the temperature of the steam boilers.The turbine discs 14 and 15 are divided into a number of annular partsso that the different parts of the discs may freely expand under theinfluence of different temperatures. Such divisions are preferablyarranged at the places where the passages 31, 36 and 35 for theextraction of steam are provided.

The remaining steam which has not been withdrawn from the turbinethrough chamber 18, forming the main'part of the admission steam, fiowsthrough the said first medium pressure stage 30 thereby giving off partof its energy by expansion to the lower temperature and lower pressureprevailing in the annular chamber 33 between the first medium pressurestage 30 and the second medium pressure stage 34. Said chamber 33communicates, by channels 35 penetrating the turbine disc 14 and thelabyrinth plates 12 and 10, with chamber 17 in side plate 3. Fromchamber 17 conduits 36, 37 and 38 conduct the steam withdrawn fromchamber 33 to a common conduit 39 leading to another feed waterpreheater 'on a temperature level corresponding to the temperature ofthe steam in chamber 33.

The quantity of steam which has not been withdrawn from chamber 33 inthe turbine flows through the second medium pressure stage 34 therebygiving off energy to the rows of blades forming said stage. Furtherquantities of steam may thereafter be withdrawn from the turbine throughchannels 36 penetrating the turbine disc 15 and the labyrinth plates 13and 11 and leading to chamber 19 in side plate 4. To this chamber anumber of conduits 40 are connected which, as will be seen from Fig. 3,radially extend therefrom and connect chamber 19 with a collector 41 inthe form of an annular chamber or conduit for steam extracted from saidchamber 19. From collector 41 a conduit 42 connected thereto leads thecollected steam to the feed water preheater of the lowermost temperaturelevel.

By arranging the tapping or extraction conduits as above described sothat a plurality of conduits are connected to the tapping chambers ofthe side plates, the advantage has been obtained, especially as far asconcerns the last, i. e. the outmost positioned tapping of the turbinewhere the specific volume of the steam is very 5? great, that in spiteof great steam volumes considerable steam quantities may be withdrawnwhile maintaining relatively small diameters of the tapping conduitsfrom the turbine system. By this arrangement the axial extension of theturbine system may be kept small so that long shaft ends and longbearing distances may be eliminated which otherwise at high turbinecapacities and high numbers of revolution may cause vibrations in thesystem of such magnitude that the safe running thereof will decrease.

, The collecting chamber 41 for steam withdrawn from chamber 19 throughconduit 40 is, as will be seen from Fig. 1, arranged outside the turbinesystem at a place where sufficient space therefor is available. Thearrangement shown in Figs. 1 and 3 of the said collector, which isannularly shaped and axially displaced some distance from the turbinesystem, is of great advantage as by such arrangement heat conductingconnections between the collector and the generator cover or the turbinehousing 9, respectively, are eliminated. By said arrangement partialheating of the said generator cover or turbine housing is eliminatedwhich otherwise may cause heat stresses inconvenient for the correctsupporting of the turbine.

The remaining steam quantity which has not been withdrawn from chamber19 further expands in the low pressure stage 45 of the turbine andfinally in the last blade row 46 of said stage having arch-curvedblades. The blades of the last blade rows of the turbine are constructedin accordance with the principles set forth in my copending applicationSerial No. 386,241 of August 16, 1929, Patent Number 1,397,172. The lastblade row (see Fig. 4) is provided with flexible blades which are curvedoutwards and obtain their operating shape due to centrifugal force, ashas been described in my copending application Serial No. 561,565 ofSeptember 8, 1931, by means of which construction up to 30% of the heatdrop of the admitted steam may be extracted in the last row of blades.Hereby a high percentage of moisture of the steam in the inner system isprevented whereby Wear of the blades within saidinner system due towater particles contained in the steam is reduced. Instead, said wearwill be concentrated at the last blade row where the last great drop ofpressure occurs. However, since most of the expansion in this stagetakes place at the outside of the blades, the larger part of themoisture has no effect on these blades. Further, since blades of thekind referred to easily may be made replaceable in their blade rings,new blades may without difficulty be inserted if considerable wearshould occur.

In order to withstand the wear of the blades due to said moisture orwater particles contained in the steam I propose to manufacture theblades from so-called nitrated steel and expose the same to a nitratingprocess, i. e. a nitration hardening which makes their surfaces veryresistant to such wear.

Y In the arrangement shown in the drawings, the tapping or extractionconduits belonging to the inner system of the turbine may, if desired athigh load, be used as admission conduits for supplying additional highpressure steam to the turbine.

By the arrangement of the steam admission to the turbine through onlyone of its side plates I reduce the loss due to leakage along theturbine shaft as the high admission pressure in my turbine is prevailingonly on the one packing of the shaft which in Fig. 4 is designated by50. On the other shaft packing 51 a pressure is prevailing correspondingto that of the first tapping chamber 18. This reduction of the leakagelosses serves to increase the economy of the steam plant rel ferred to,i. e. in turbines of high admission pressure, for instance amounting to50-100 atm., for which pressures my turbine is applicable. The shaftpackings 50 and 51 are in known manner constructed as labyrinth.packings and, as indicated by dotted lines in Fig. 4, connected withexhaust conduits for leakage steam or with conduits through whichsealing steam in known manner is supplied to the packings.

Though steam is admitted to my turbine through one of its side platesonly, suiiicient admission areas are obtained for creating 50,000100,000 kw output in the turbine due to the specific volume of theadmission steam at said high pressures being very small. The provisionof sufficiently large admission areas in the turbine disc 14, i. e.sufliciently wide channels 20 therein, is facilitated by my method offastening the turbine discs on the shaft ends shown in Fig. 4. Due tothe arrangement of the tapping chambers in both side plates of theturbine, the channels for tapping steam will penetrate the turbine discsor the labyrinth plates, respectively, at different radial distancesfrom the centre of rotation of the turbine.

What I claim is:-

1. A steam or gas turbine of the double rotation type having incombination with the turbine casing, a collector chamber inside theturbine casing and axially displaced from the central plane of theturbine, and a plurality of tapping or extraction chambers for fluidfrom difierent pressure and temperature stages of the turbine, thetapping chamber corresponding to the lowermost pressure stage beingprovided with a plurality of tapping conduits connecting said chamberwith said collector chamber.

2. A steam or gas turbine of the double rotation type having incombination with the turbine casing, an annular collector chamber insidethe turbine casing, and a plurality of annular tapping or extractionchambers for fluid from different pressure and temperature stages of theturbine, the tapping chamber corresponding to the lowermost pressurestage being provided with a plurality of tapping conduits extendingradially therefrom to said collector chamber.

3. A steam or gas turbine of the double rotation type comprising incombination with the rotatable blade-carrying members a plurality oftapping or extraction chambers at the sides of said blade-carryingmembers respectively in communication with different pressure andtemperature stages of the turbine, an annular collection chamber for afluid of relatively low temperature and pressure, and a plurality ofradially disposed conduits distributed around the axis of the turbineand in communication with said collection chamber and the tappingchamber which corresponds to the lowermost pressure stage.

4-. A steam or gas turbine of the double rotation type comprising incombination with the rotatable blade-carrying members a plurality oftapping or extraction chambers at the sides of said blade-carryingmembers respectively in communication with different pressure andtemperature stages of the turbine, an annular collection chamber for afluid of relatively low temperature and pressure, and a plurality ofradially disposed conduits distributed around the axis of the turbineand in communication with said collection chamber and the tappingchamber which corresponds to the lowermost pressure stage, saidcollection chamber being displaced both axially and radially withrespect to said blade-carrying members.

5. A steam or gas turbine of the double rotation type comprising, incombination with rotatable blade-carrying members, an annular tapping orextraction chamber adjacent to one of said members and in communicationwith a relatively low pressure stage of said turbine, an annularcollection chamber of larger diameter than said tapping or extractionchamber for collecting fluid from said tapping or extraction chamber,and a plurality of conduits connecting said tapping or extraction andsaid collection chambers.

6. A steam or gas turbine of the double rotation type comprising, incombination with rotatable blade-carrying members and a casing enclosingthe same, an annular tapping or extraction chamber adjacent to one ofsaid members and in communication with a relatively low pressure stageof said turbine, an annular collection chamber for collecting fluidreceived from said tapping or extraction chamber, and a plurality ofconduits connecting said tapping or extraction and said collectionchambers, said collection chamber being displaced axially and radiallyfrom the blade-carrying members but disposed within the turbine casingin surrounding relation with the end of the machine driven thereby.

FREDRIK LJUNGSTRDM.

